Molecular imaging is a new discipline that makes possible the noninvasive visualization of cellular and molecular processes in living subjects. Here we will adopt the reporter gene and reporter probe imaging technique (developed initially for cancer researchers) to solve a different important problem in cardiology (i.e., understand pharmacokinetics and biodistribution of cardiac stem cell therapy). In particular, we will develop and validate various reporter genes that will enable us to image fate of cardiac stem cells (CSC) in vivo. We will use clinical positron emission tomography and computed tomography (PET/CT) and magnetic resonance imaging (MRI) to track the survival, proliferation, and function of transplanted cells in pre-clinical large animal models. The information gathered from these studies should prove instrumental for marrying molecular imaging with clinical stem cell therapy in the future.